The opening image features a linear fracture with aligned pits within the impact melt deposit on the floor, and a crater which may have formed by collapse of impact melt (collapse pit rather than an impact crater). The fracture may have formed as a tube collapsed. Lava tubes commonly form within basaltic volcanoes on Earth, as part of an underground plumbing system that moves magma away from a vent. The same type of tubes and pits probably formed in lunar mare (also basalt). Should we expect lava tubes in impact melt deposits? There is much evidence for such in the NAC images collected over the past few years.

The NAC revealed collapse pits, often aligned in rows, in many impact melt deposits. These pits are similar to collapse pits found in lava tubes on the Earth (often called skylights). In one case two collapse pits side-by-side resulted in a natural bridge! But how did they form? What caused the melt to flow after it ponded in the crater floor? Perhaps slumps of wall material into the melt caused large-scale displacements of still molten subsurface melt to flow. Or perhaps over months and years the crater floor rebounded while melt was still cooling beneath a crust. Both likely happened, so it is not a big surprise that melt moved in subsurface tubes for quite a while after the impact event.

Comparison of today's mosaic with the oblique image of the central
peaks. Top of the images is west. Images are 34 km across
[NASA/GSFC/Arizona State University].

The interior of Copernicus contains dramatic impact melt features. The image below (a subsampled portion of the full mosaic) shows a section of the northern wall of Copernicus. The top of the image shows the edge of an impact melt pool emplaced on a small terrace. At some point, a portion of melt escaped the terrace and the liquid rock carved curved, sinuous channels as it flowed down the wall. Towards the bottom of the image you can see where one of the flows stopped, spread out, and deposited some of the impact melt.

Impact melt flowed from terraces down the north wall of Copernicus,
leaving behind curved channels. Field of view is 6480 meters [NASA/GSFC/Arizona
State University].

The subsampled mosaic shows a dramatic view of the impact melt in Copernicus crater's floor. The melt in the eastern portion of the image shows several mounds, while the melt on the western half of the mosaic is noticeably smoother. Several terraces at different elevations along the northern wall also have melt ponds. How does Copernicus crater's impact melt compare to other large craters? Tycho crater has a similarly large sheet with a mix of chaotic and smooth melt. As does King crater, Necho crater, Giordano Bruno crater, and almost every other Copernican aged crater larger than 1 km in diameter!

Subsampled version of the Copernicus mosaic. Image field of view 36.5 km across [NASA/GSFC/Arizona State University].

Explore the entire Copernicus mosaic! And compare with the Copernicus peak oblique from yesterday's Featured Image. The mosaic images were taken only 8-10 orbits after the oblique image of Copernicus to maintain similar viewing geometry, making visual comparisons even easier!

On 5 August and 13 August 1970, NASA Administrator Thomas Paine dispatched letters on the future of the U.S. lunar program to the Lunar and Planetary Missions Board (LPMB) and the Space Science Board (SSB) of the National Academy of Sciences National Research Council. In his letters, he outlined three options for curtailing Project Apollo. Of these, the first (Option I) would cancel one Apollo mission, while the others would nix two. The options he described were in part aimed at avoiding a delay in the Skylab Program, which constituted a step toward Paine’s favorite 1970s NASA goal: a 12-man Earth-orbiting space station that would be staffed and resupplied using a fully reusable space shuttle. Members of the LPMB and the SSB held an urgent two-day meeting (15-16 August 1970) in Woods Hole, Massachusetts, to develop a response to Paine’s letters.

By the time the LPMB and SSB met, NASA had flown three manned lunar landing missions: Apollo 11 (16-24 July 1969), which landed off-target on Mare Tranquillitatis; Apollo 12 (14-24 November 1969), which landed close by the derelict Surveyor 3 automated lander on Oceanus Procellarum, thereby demonstrating the pinpoint landing capability essential for geologic traverse planning; and perilous Apollo 13 (11-17 April 1970), which suffered an oxygen tank explosion in its Command and Service Module (CSM) that scrubbed its planned landing at Fra Mauro. Of these, Apollo 11 and Apollo 12 were mainly engineering missions intended to prove the Apollo system, while Apollo 13 had been intended as the first science-focused mission. Paine had canceled one Apollo mission, Apollo 20, in January 1970 so that its Saturn V rocket could launch the Skylab Orbital Workshop into low-Earth orbit. That left six moon landings before the program concluded with Apollo 19.

The program meant to extend piloted lunar exploration deep into the 1970s, the Apollo Applications Program (AAP), had taken repeated funding hits since 1967, and so had abandoned its lunar ambitions, becoming the strictly Earth-orbital Skylab Program in February 1970. Some concepts proposed for AAP lunar missions – for example, three-day lunar surface stays and a manned roving vehicle – would find their way into Apollo before its end, but when Apollo ended, so would end piloted lunar exploration.

With the goal of a man on the moon by 1970 successfully attained, pressure had begun to build to cancel some or all of the remaining Apollo lunar missions. In the aftermath of the Apollo 13 accident, some policy-makers questioned the wisdom of continuing to place astronauts at risk. Apollo 11 had humbled the Soviets on the technological prestige front of the Cold War; future landings would do little to enhance prestige, they argued, but a single lost crew could erase much of what the U.S. had gained by being first on the moon.

In addition, President Richard Nixon’s Office of Management and Budget was eager to rein in Federal expenditures. By mid-1970, the United States was spending roughly the entire $25-billion cost of the Apollo Program every 10 weeks to wage war in Indochina. Though NASA’s budget had fallen to only about $4 billion in 1970, the agency still constituted a highly visible and thus highly vulnerable target for new cuts.

"In their joint response to Paine, dated 24 August 1970, LPMB chair John Findlay and SSB chair (and Nobel Laureate) Charles Townes reminded Paine that past scientific advisory boards – including one Townes had chaired, which prepared a January 1969 report for then-President-elect Nixon – had advised that NASA should continue manned lunar exploration throughout the 1970s, and that from 10 to 15 manned moon landings should be flown. They cited this when they refused to consider cutting more than one Apollo mission. The Townes Committee had, incidentally, expressly opposed Paine’s large Earth-orbiting station.

"Apollo, they told the NASA Administrator, was of the greatest scientific importance. They explained that “the Apollo missions do not simply represent the study of a specific small planet but rather form the keystone for a near term understanding of planetary evolution.”

In their joint response to Paine, dated 24 August 1970, LPMB chair John Findlay and SSB chair (and Nobel Laureate) Charles Townes reminded Paine that past scientific advisory boards – including one Townes had chaired, which prepared a January 1969 report for then-President-elect Nixon – had advised that NASA should continue manned lunar exploration throughout the 1970s, and that from 10 to 15 manned moon landings should be flown. They cited this when they refused to consider cutting more than one Apollo mission. The Townes Committee had, incidentally, expressly opposed Paine’s large Earth-orbiting station.

Apollo, they told the NASA Administrator, was of the greatest scientific importance. They explained that “the Apollo missions do not simply represent the study of a specific small planet but rather form the keystone for a near term understanding of planetary evolution.” They then wrote that

"We respect the serious fiscal and programmatic constraints…. However, it should be recognized that any reduction in the number of missions will seriously threaten the ability of the total Apollo program to answer first-order scientific questions. We are on the very beginning of a learning curve, and it is clear that the loss of one mission will have much greater than a proportional effect on the instrumented experiments and, more critically, on the design and execution of the geology experiments involving the astronauts."

Findlay and Townes explained that at Woods Hole the LPMB and SSB had considered three options for Apollo’s future, all different from Paine’s three options. Option I was to fly missions 14, 15, 16, and 17 about six months apart, fly missions to the Skylab A Orbital Workshop over a period of about 20 months, and then carry out Apollo missions 18 and 19 six months apart.

Missions 14 and 15 would be H-class walking missions, as had been 12 and 13; 16 and subsequent would be J-class missions. The latter would include a Lunar Module (LM) capable of increased lunar surface stay time, a rover, improved lunar surface experiments, remote sensors on the CSM in lunar orbit, and a CSM-released lunar subsatellite. The long gap between Apollo 17 and 18 would permit lunar scientists to digest data from the previous missions and to design new experiments for the final mission pair. Findlay and Townes noted, however, that the gap might also make Apollo 18 and 19 vulnerable to budget cuts. Paine’s Option I had cut Apollo 15 and flown all the remaining lunar missions before Skylab A.

The LPMB and SSB’s Option II was to cut Apollo 15, fly 14, 16, 17, 18, and 19 about six months apart, and then fly the Skylab A missions. Their Option III was to cut Apollo 15, fly 14, 16, 17, 18, and 19 five months apart, and then fly Skylab A. Paine’s Options II and III had both omitted 15 and 19.

As might be expected, the LPMB and SSB favored their Option I, which cut no missions. If, on the other hand, “retreat from Option I proves unavoidable,” they recommended their Option III. This would, they explained, sacrifice Apollo 15 to save Apollo 19, which, they explained, would include 20% of the Apollo program’s moonwalk time and cover 25% of the total area to be included in Apollo traverses. In addition, by reducing the time between launches, they hoped to limit the costly delay in Skylab A’s launch.

They conceded that most of the experiments planned for Apollo could be carried out even if both Apollo 15 and 19 were cut. However, an automated station in the passive seismic network would be lost, surface samples would not be obtained from two geologically significant locations, and several experiments would be flown only once, so would have no backup. They concluded by reiterating that the cuts Paine envisioned could prevent lunar scientists from answering first-order questions about the moon, and added that “the consequences of such failure for the future of [NASA] and, we believe, for large-scale science in this country are incalculable.”

The VYOM Sounding Rocket, designed by students at theIndian Institute of Space Science and Technology (IIST),is prepared for its launch into the "cloud-laden skiesabove the Arabian Sea, May 18, 2012 [IIST].

Thiruvananthapuram - IIST (The Hindu, June 28) Former President and space scientist Dr. A.P.J. Abdul Kalam has proposed that India take up a manned space mission to the moon and Mars.

He also proposed the development of solar sails for interplanetary missions and an integrated disaster management system using space technology.

Mr. Kalam, who is the Chancellor of the IIST, said India could come up with navigational satellites and a mechanism for refuelling, repair, and maintenance of satellites in geostationary orbit.

Vision Plan - He told the gathering of students, parents, faculty of the IIST, and scientists from ISRO that the new programmes, if taken up under the ISRO vision 2030 plan, could open up new opportunities and challenges for the scientific community and the youth of India.

Mr. Kalam said fully reusable space transportation systems with high payload efficiencies were essential for space missions in future. Such systems, he added, depended on critical technologies such as in-flight air collection and oxygen liquefaction, ram/ scramjet engines, ascent turbojet/turbofan ramjet engines, and advanced lightweight high temperature materials.

Global Demand - Highlighting the need to bring down the iron curtain between technological groups, Mr.Kalam said the global demand was shifting towards the development of ecologically sustainable systems integrating science, technology, and environment.

“The real challenge for the scientific community is to use technology to enrich the life of 750 million rural people.”

He said research in basic sciences was crucial if India was to remain competitive at the global level and develop cost-effective technologies for the common man.

Earlier, Mr. Kalam conferred the B.Tech. degree on 125 students of the first batch of the IIST who graduated in Aerospace Engineering, Avionics, and Physical Sciences.

He also released a book A Brief History of Rocketry in ISRO authored by P.V. Manoranjan Rao and P.Radhakrishnan. Former chairman of the Atomic Energy Commission Srikumar Banerjee was the chief guest at the convocation ceremony.

ISRO chairman K.Radhakrishnan, who is also the chairman of the board of management, IIST, Director of the institute K.S. Dasgupta, and former director B.N.Suresh addressed the gathering.

Wednesday, June 27, 2012

The central peaks of Copernicus crater cast a long shadows to the west
over a crater floor that was flooded with impact melt that cooled and
hardened to form this spectacular landscape. LROC NAC M193025138LR, image field of view is a 1350 meter section from this spectacular, new oblique mosaic showing the entire 90 km-wide interior of Copernicus, HERE [NASA/GSFC/Arizona State University]

Sarah Braden

LROC News System

On May 5th, 2012 LRO slewed 63° to capture this LROC image of the interior of Copernicus crater (9.62°N, 339.92°E, 93 km in diameter). The central peaks immediately capture your eye, with the tallest peak rising one kilometer above the floor of the crater. For comparison, the Grand Canyon has an average depth of 1.6 km. During the impact that formed Copernicus crater, an unimaginable amount of kinetic energy was transferred instantaneously into the surface. After the excavation stage of the impact, the initial transient crater collapsed under the force of gravity causing the crater rim to move inward, and the central region rebounded (uplifts) to form the central peaks! Central peaks only form in craters larger than 15-20 km in diameter on the Moon. The rock that forms the central peak originates from the greatest depth of all the material excavated by the crater. For that reason, scientists are very interested in the composition of central peaks, since the material tells us what lies deep beneath the surface of the lunar crust; studying central peaks of large craters is therefore one of the best ways, absent returned samples, to probe the composition of the lunar interior. Recent remote sensing studies using Moon Mineralogy Mapper spectra confirmed the presence of relatively unusual olivine-rich material in the central peaks of Copernicus. Are we sensing the upper portions of the mantle, or magma chambers that formed in the crust?

Rough vector of the view over the central peaks seen in the LROC Featured Image, released June 27, 2012. From
LROC WAC observation M147109260C,
orbit 6813, December 16, 2010; resolution 60.3 meters per pixel at an
incidence angle of 78° from 43.13 kilometers [NASA/GSFC/Arizona State
University].

Context image of Copernicus crater. The Featured Image is approximately bounded by the red box. Copernicus crater is 93 km in diameter, and the image width is 120 km [NASA/GSFC/Arizona State University].

Copernicus crater also plays an important role in our understanding of the lunar geologic timescale. Scientists use the basic principles of stratigraphy and superposition to define relative ages for geologic terrains and features. Rays are young lunar features, and any geologic unit covered by a ray of Copernicus must be relatively older than the crater itself. In fact Copernicus crater is defined as the beginning of the youngest period of lunar geologic history, the Copernican period. But how young are Copernican materials? It wasn't until the first samples were brought back from the Moon, from the Apollo and Luna missions, that scientists were able to tie relative ages to absolute time within the lunar timescale. It is likely that Apollo 12 astronauts sampled material ejected from the impact that formed Copernicus crater. These samples were radiometrically age dated to be close to 800 million years old! So all materials mapped stratigraphically as Copernican are younger than 800 million years. Of course the sample collected at the Apollo 12 site is thought to be from Copernicus crater, not known to be. Many craters are much younger, so you can think of Copernicus as the oldest young crater on the Moon (see yesterday's LROC Featured Image on Giordano Bruno crater).

Copernicus crater was a candidate landing site for the Apollo 18 lunar landing mission, which was unfortunately cancelled. The Constellation Program also designated Copernicus crater as a region of interest. So perhaps in the future astronauts will visit Copernicus crater, but when? In the meantime scientists are using LRO data to understand the complex geology of this important crater and plan future exploration.

The floor of Copernicus crater is covered with rock formed as a sea
of impact melt froze. There are many cracks and pits that tell a story
of how the once molten rock moved around in the crater floor, a topic
for a future Featured Image. (See "Failed Skylights of Copernicus," January 24, 2012) Image width is 1350 m [NASA/GSFC/Arizona State University].

LROC took another oblique view of a much younger Copernican crater, Tycho (43.37°S, 348.68°E, 85 km in diameter), which is only about 110 million years old. Even though Tycho is smaller in diameter than Copernicus, the summit of Tycho's central peak is 2 km above the crater floor! That is twice as tall as Copernicus crater's central peak. The final form of a crater transitions with the size and speed of the impactor. Craters even larger than Copernicus do not have central peaks at all, but rather peak rings. You can compare the full resolution Tycho oblique view with the Copernicus oblique view.

To conserve fuel, LRO was moved from its 50-km circular orbit into an elliptical orbit on 11 December 2012. As a result the spacecraft's altitude is now significantly higher in the northern hemisphere; the low point of the orbit is ~30 km over the south pole and 200 km over the north pole. This new orbit provides fantastic opportunities to acquire large area mosaics with nearly identical lighting across numerous orbits. For this Giordano Bruno crater mosaic, LROC acquired four NAC pairs (8 NAC images), from 4 orbits in a row, over a six hour period on 1 March 2012. Since LRO's polar orbits progress from east to west, the first image pair was acquired by slewing the spacecraft 6° to the west, on the next orbit only 1° to the west, on the third orbit LRO slewed 4° to the east, and the last orbit 9° to the east. The pixel scale of the images was about 1.6 to 1.8 meters, so the the images were reprojected to 1.8 meters.

How did Giordano Bruno (35.92°N, 102.74°E) crater form, how big is it, and when did it form? The first question is easy: it formed as the result of a hypervelocity impact of a comet or asteroid into the Moon. The crater is irregularly shaped, so its diameter ranges from about 20.9 km to 21.6 km (13.0 miles to 13.4 miles). Its walls are very steep and the floor is a mix of jagged boulders and pooled impact melt rock. Since LROC has an ability to collect stereo observations, we now have a high-resolution topographic map of the whole crater made from images acquired when LRO was in its lower orbit (50 cm resolution).

The NAC topography reveals that the walls everywhere have over 2000 meters of relief, and the northwest side of the crater has more than 2800 meters of relief. Everywhere the wall slopes exceed 30°, which is very near the angle of repose. However, in the upper portions of the walls the slopes are 40° or more. Slopes this steep can only be supported by solid material, not loose debris. Over time smaller impacts will erode the upper walls, and all slopes will be at or less than the angle of repose as the walls literally crumble. In the topographic map (above) you can also see a large bench that represents a block of wall material that slumped into the crater, but stopped about two thirds of the way down. That bench used to be at the same level as the rim, some 1500 meters up the wall!

Impact melt flow on south flank. View the original field of view HERE [NASA/GSFC/Arizona State University].

How old is this beautiful crater? The answer is very young, but how young? We won't know the answer for sure until we obtain a sample of impact melt and can make precise radiometric age dates. The sharp, well preserved nature of the melt forms on the crater floor and flanks (above) and the sparsity of superposed craters show us that the crater is young. Scientists have counted the number of craters to estimate an age of 10 million years, or less. However with craters this young we do not know how many of the few craters that we can see were actually formed as self-secondaries: late stage material ejected from the event that formed the crater and fell back on the newly formed ejecta. These self-secondary craters, if they exist in abundance, would lead to an estimated age that is older than the true age, if not accounted for in the crater statistics.

Enigmatic dark ejecta on north flank. View the wider field of view, HERE [NASA/GSFC/Arizona State University].

Many fascinating details are revealed both inside and outside the crater in the NAC images. What is the dark rubbly material that occurs in discrete patches on the rim (above)? Could it be material from basaltic dikes excavated from depth and ejected up onto the rim? Or perhaps impact melt glass? This question may remain outstanding until astronauts traverse the rim of this spectacular crater. Imagine standing and looking across a 2500 meter (8200 feet) deep crater to the far wall some 21 km (13 miles) distant. For comparison the Grand Canyon is only 1800 meters (6000 feet) deep, but is a bit wider at 29 km (18 miles). Which would be more impressive? I am not certain, but I would certainly like to find out!

Examine this full resolution (1.8-meter per pixel scale) mosaic of Giordano Bruno HERE.

From year to year, the moon never seems to change. Craters and other formations appear to be permanent now, but the moon didn't always look like this. Thanks to NASA's Lunar Reconnaissance Orbiter, we now have a better look at some of the moon's history [NASA GSFC SVS].

Friday, June 22, 2012

An oblique view of Mare Ingenii and the swirl that marks its floor.
Scene is approximately 15 km across (subsampled from the native
resolution); LROC Narrow Angle Camera (NAC) frames M191830503L & R, LRO orbit 13304, May 16, 2012; resolution 2.95 meters per pixel. See the full size LROC Featured Image HERE [NASA/GSFC/Arizona State
University].

Lunar swirls are among the most beautiful and bizarre features on the Moon. Seen as bright, sinuous regions, swirls are associated with weak magnetic anomalies in the Moon's crust. Images from LROC, and the topographic information extracted from those images, have shown that swirls have no topography associated with them; they are not higher or lower than their surroundings. Instead, it is as if someone has taken a brush and laid down a beautiful swath of bright paint. In the top image is the classic omega-shaped swirl of Mare Ingenii, also seen in this past featured image. The region of higher terrain is the rim of Thompson crater.

The lavas that formed Mare Ingenii flooded Thompson, leaving only the rim as a kipuka of older highland terrain.

A wider (but very reduced-resolution) view of the Ingenii swirls. The rims of
Thompson and Thompson M craters are seen in the foreground. View is
from east to west, and the full scene is approximately 58 km across
[NASA/GSFC/Arizona State University].

The obvious question: how did swirls, like the one shown here, form? The leading hypothesis involves two main components - solar wind and crustal magnetic anomalies. The solar wind is a stream of charged particles coming from the Sun that normally interact with the Moon's surface, darkening it as one portion of a process called space weathering. On the Earth, the magnetic field acts as a shield and usually deflects the solar wind (when it doesn't, the solar wind interacts with the atmosphere, causing the northern lights). The Moon lacks a global magnetic field, but does have small, local magnetized regions within the crust. This is where we see the swirls. So the idea is that these local magnetic fields prevent the solar wind from doing its normal job of space weathering, and the surface stays bright. The stunning swirly pattern of the bright regions is likely due to the complex pattern of the magnetic field lines, which shield some areas and not others.

LROC Wide Angle Camera (WAC) views of Mare Ingenii, for context. The box in the second image outlines
the approximate footprint of the LROC Featured Image released June 21, 2012. The bottom animated gif image, generated from separate views of the 282 km wide Mare Ingenii and the 1400 square km surrounding region from the LROC QuickMap. Resolution was set at 500 meters, WAC mosaic draped over the WAC derived elevation model Researchers long suspected true lunar albedo swirls are not related to any topographic feature, including very small secondary craters. The latest high resolution images and crater count studies continue to back that conclusion. [NASA/GSFC/Arizona
State University].

The LROC team is continuing to study the lunar swirls, including their color properties as observed in LROC Wide Angle Camera data, to learn more about how swirls form, the process of space weathering, the rate at which bright, freshly exposed material is darkened by space weathering, and why crustal magnetic fields are where they are.

See the spectacular full-resolution oblique look at the Ingenii swirls HERE.

Thursday, June 21, 2012

One of two surplus Soviet-era ALMAZ "gunboat" space stations arrives at
Excalibur, on the Isle of Man. The company hopes to charge customers
$156 million for round-trip orbital excursions to the Moon by 2015. The formerly secret station cores are similar in design to the Soviet Salyut space stations [AmadeusPhotography.com].

Isle of Man based space tourism firm Excalibur Almaz has said that it will be ready to rocket the rich to the Moon by 2015.

The company told a space tourism conference that it was planning the first test flight of its fleet of second-hand ex Soviet capsules and space stations in 2014 and would be ready to send a well-off civilian on a lunar trip the following year, The Telegraphreports.

The company has so far purchased four capsules and two disused space stations - once part of the Soviet era "Almaz" ("Diamond") program - from the Russians, and plans to get launch rockets from the same source.

Excalibur Almaz is that same firm that said back in 2009 that it would be offering week-long tourist trips in space from 2013 for $35m. So clearly, it's moved a deadline or two before, and the price has also gone up by quite a lot. The firm reckons the first few trips to the Moon will cost £150m, falling to £50m over the next ten years of trips.

Spoke too soon! When JAXA released this Kaguya Terrain Camera image, showing the deep interior of Shackleton crater for the first time in 2008, scientists claimed it disappointingly showed no indication of ice, though no one yet can say how a slurry of lunar volatiles might appear. Now, however, researchers analyzing laser altimetry returned by the LOLA instrument on-board the Lunar Reconnaissance Orbiter (LRO) cite strong evidence of ice content in the permanently shadowed interior. The Moon's south pole is serendipitously situated on Shackleton's rim, directly under all of LRO's nearly twenty thousand polar orbits since 2009, affording extraordinary study [JAXA/SELENE]..

If humans are ever to inhabit the moon, the lunar poles may well be the location of choice: Because of the small tilt of the lunar spin axis, the poles contain regions of near-permanent sunlight, needed for power, and regions of near-permanent darkness containing ice — both of which would be essential resources for any lunar colony.

The area around the moon’s Shackleton crater could be a prime site. Scientists have long thought that the crater — whose interior is a permanently sunless abyss — may contain reservoirs of frozen water. But inconsistent observations over the decades have cast doubt on whether ice might indeed exist in the shadowy depths of the crater, which sits at the moon’s south pole.

Now scientists from MIT, Brown University, NASA’s Goddard Space Flight Center and other institutions have mapped Shackleton crater with unprecedented detail, finding possible evidence for small amounts of ice on the crater’s floor. Using (the LOLA) laser altimeter on the Lunar Reconnaissance Orbiter (LRO) spacecraft, the team essentially illuminated the crater’s interior with laser light, measuring its albedo, or natural reflectance. The scientists found that the crater’s floor is in fact brighter than that of other nearby craters — an observation consistent with the presence of ice, which the team calculates may make up 22 percent of the material within a micron-thick layer on the crater’s floor.

In addition to the possible evidence of ice, the group’s map of Shackleton reveals a “remarkably preserved” crater that has remained relatively unscathed since its formation more than three billion years ago. The crater’s floor is itself pocked with several smaller craters, which may have formed as part of the collision that created Shackleton.

The crater, named after the Antarctic explorer Ernest Shackleton, is more than 12 miles wide and two miles deep — about as deep as Earth’s oceans. Maria Zuber, the team’s lead investigator and the E.A. Griswold Professor of Geophysics in MIT’s Department of Earth, Atmospheric and Planetary Sciences, describes the crater’s interior as “extremely rugged … It would not be easy to crawl around in there.”

Mapping the dark. Slipping past the Moon's south pole on the brightly lit rim of Shackleton crater, the dark of the permanently shadowed interior of the crater quickly overtakes a very steep crater wall, like the terrestrial oceans. LRO has skipped through thousands of polar orbits eventually carrying the vehicle over every area on the Moon's surface and over Shackleton, high at the top of everyone's list of priority targets, during every orbit, LROC Narrow Angle Camera (NAC) M142464150L, LRO orbit 6128, October 23, 2010, 89.21° angle of incidence, 0.87 meters resolution from 41.91 kilometers [NASA/GSFC/Arizona State University].

The group was able to map the crater’s elevations and brightness in extreme detail, thanks in part to the LRO’s path: The spacecraft orbits the moon from pole to pole as the moon rotates underneath. With each orbit, the LRO’s laser altimeter maps a different slice of the moon, with each slice containing measurements of both poles. The upshot is that any terrain at the poles — Shackleton crater in particular — is densely recorded. Zuber and her colleagues took advantage of the spacecraft’s orbit to obtain more than 5 million measurements of the polar crater from more than 5,000 orbital tracks.

“We decided we would study the living daylights out of this crater,” Zuber says. “From the incredible density of observations we were able to make an extremely detailed topographic map.”

The team used the (LOLA) to map the crater’s elevations based on the time it took for laser light to bounce back from the moon’s surface: The longer it took, the lower the terrain’s elevation. Through these measurements, the group mapped the crater’s floor and the slope of its walls.

A quaking theory.The researchers also used the laser altimeter to measure the crater’s brightness, sending out pulses of infrared light at a specific wavelength. The crater’s surface absorbed some light based on its own natural albedo, reflecting the rest back to the spacecraft. The researchers calculated the difference, and mapped the relative brightness throughout the crater’s floor and walls.

While the crater’s floor was relatively bright, Zuber and her colleagues observed that its walls were even brighter. The finding was at first puzzling: Scientists had thought that if ice were anywhere in a crater, it would be on the floor, where very little sunlight penetrates. The upper walls of Shackleton crater, in comparison, are occasionally illuminated, which could evaporate any ice that accumulates.

How to explain the bright walls? The team studied the measurements, and came up with a theory: Every once in a while, the moon experiences seismic shaking brought on by collisions, or gravitational tides from Earth. Such “moonquakes” may have caused Shackleton’s walls to slough off older, darker soil, revealing newer, brighter soil underneath.

Until very recently luna incongnita, the permanently shadowed 10.3 km-wide interior of Shackleton, shouldering the Moon's south pole (blue arrow), today seems much like hundreds of other lunar craters of similar age and dimension. Its ink-black interior has steadily been brightly unveiled in a steady build-up of laser data points collected over the course of three years in polar orbit by the LOLA instrument on LRO. As it is on Earth, however, in Real Estate, "location is everything" [NASA/GSFC/LOLA].

Zuber says there may be multiple explanations for the observed brightness throughout the crater: For example, newer material may be exposed along its walls, while ice may be mixed in with its floor. Her team’s ultra-high-resolution map, she says, provides strong evidence for both.

“Ice in the polar regions has been sort of an enigmatic thing for some time … I think this is another piece of evidence for the possibility of ice,” Bussey says. “To truly answer the question, we’ll have to send a lunar lander, and these results will help us select where to send a lander.”

Zuber adds that the group’s topographic map will help researchers understand crater formation and study other uncharted areas of the moon.

“I will never get over the thrill when I see a new terrain for the first time,” Zuber says. “It’s that sort of motivation that causes people to explore to begin with. Of course, we’re not risking our lives like the early explorers did, but there is a great personal investment in all of this for a lot of people.”

Japan's scientists may have leaped to conclusions when they over-confidently announced there was no ice inside Shackleton (upper left), after releasing the first image of the crater's interior a few years ago, but their iconic high-definition image of an orbital Earthrise from November 2007 still takes the breath away [JAXA/NHK/SELENE].

Five to ten kilometer resolution map of Thorium, related to the lunar surface in parts per million by Japan's lunar orbiter Kaguya. While many have long noted the practical mineral wealth on the Moon, as Joshua E. Keating draws those threads together below, the Moon's most valuable resource is probably still its proximity and its volatiles just outside Earth's gravity well.

Joshua E. KeatingForeign Policy Blog

In a new article for Foreign Policy, John Hickman ponders what the political ramifications might be if China were to declare sovereignty over a swath of territory on the moon, triggering a lunar land grab. But what about the economics of this extraterrestrial Great Game? Maintaining a permanent manned presence on the moon is an awfully pricey undertaking just to make a political statement. Is there any way to make some money from mining the moon's riches?

Possibly, but it's a long-term investment. The biggest cheese on the moon is probably helium-3, an isotope that's abundant in the moon's regolith, but rare and getting rarer here on Earth. Helium-3 is currently used mostly for scientific research, but some see it as a future source for non-radioactive fusion power. Unfortunately, the United States and Soviet Union exhausted much of the world's supply during Cold War-era nuclear tests. Several private companies, including Silicon Valley's Moon Express, are exploring the development of helium-3 mining on the moon and governments including India and Russia have discussed the possibility. (It's also the basis of the plot for the 2009 movie Moon.)

It's hard not to be enticed by the numbers. Gerald Kulcinski, director of the Fusion Technology Institute at the University of Wisconsin, estimated when contacted by Foreign Policy that given the potential energy of a ton of helium-3 (the equivalent of about 50 million barrels of crude oil) and the estimated amount of recoverable helium-3 (around 75,000 tons, or 15 percent of the total amount on the moon) we could be looking at around $375 trillion worth of the stuff.

Wednesday, June 20, 2012

A small section of an enormous, now frozen, river of impact melt that
flowed down the southeastern flank of Tycho crater some 108 million
years ago. LROC Narrow Angle Camera (NAC) observation M185940195RE,
LRO orbit 12480, March 9, 2012; angle of incidence 46.55° at 0.64
meters resolution from 61.72 kilometers. View the full-size 1000 x
1000px LROC Featured ImageHERE [NASA/GSFC/Arizona State University].

Jeffrey PlesciaLROC News System

Impact melt is one of most spectacular products of impact cratering events. A comet or asteroid impacts the Moon at 10-60 km/sec, and releases so much energy that it melts a significant amount of the target rock. The larger the projectile, the bigger the crater, and the more melt that is produced. While much of the Tycho impact melt pooled on crater floor, some of it was thrown out of the crater onto the rim. A large mass of impact melt landed on the southeastern rim and flowed down the rim filling low areas and then spilling over and continuing downhill. Between pools, the melt formed narrow flows whose width was controlled by the topography.

The context image (sub-sampled NAC mosaic) below shows a wider view of the impact melt deposit extending down slope from a high pool (on the left side of the image) at an elevation of about -310 m to a lower pool on the (on the right side of the image) that lies more than 600 m downslope (elevation -950 m). The flow is about 5000 m long; its width ranges from 300 to 700 m and is controlled by the topography of the surrounding hills. The texture of the flow surface and the formation of channels on its eastern end (above and below the crater) is a function of the slope of the underlying surface, and the changes in viscosity of the melt as it cools.

This contextual montage of the corresponding left and right frames of
LROC NAC observation M185940195 allows this view of spectacular river of impact melt, now frozen, that briefly flowed down the southeastern flank of Tycho crater. View the spectacular full-size (2000 x 800px) context view HERE [NASA/GSFC/Arizona State University].

Contextual LROC Wide Angle Camera (WAC) image of the various pools and
their elevations. Over distances of 10-20 km, the melt flowed down
almost a kilometer in elevation. The white box roughly outlines the
field of view shown in detail immediately above. LROC WAC observation M177698611C
(604nm), orbit 11323, December 5, 2011, illumination from the northeast
(upper right) at an 80.34° angle of incidence; 59.83 meters resolution,
from 43.7 kilometers. View the original annotated context image HERE [NASA/GSFC/Arizona State University].

The last pool (-950 m elevation) to be filled by this melt flow has well preserved sharp morphologic features that tell scientists much about the history of emplacement. The overall pool is about 4500 meters long by 2100 meters wide.

Context image of the lowest pool of impact melt, showing the locations
of higher resolution images below. Cropped with depth distortion from the full size context image
accompanying the LROC Featured Image, released June 20, 2012. From a
montage of the corresponding left and right frames from LROC NAC
observation M181222542LR,
orbit 11820, January 14, 2012; resolution 1.3 meters from 62.98
kilometers, angle of incidence 72.72° [NASA/GSFC/Arizona State
University].

The impact melt flowed (A) eastward down a narrow valley from a higher pool to the west, then draining into and filling a depression at a lower elevation. To the east of the crater, the flow is about 250 m wide and exhibits a well-defined channel with levees about 60 m wide. Farther east the flow broadens into a large pool. Later a 400 m impact crater formed in hardened impact melt ejecting boulders up to 20 meters in diameter. This crater provides a great section through the flow for future geologists roaming about this geologic wonderland!

The upper right portion of image (B) shows a wrinkled flow surface with ridges spaced about 30-40 m apart; the lower left portion of the flow has a smooth surface. The two different surfaces suggest that there were different pulses of impact melt entering the pool. An initial pulse formed a relatively smooth surface, then a second pulse of melt entered the pool wrinkling part of the crust. As a crust formed on the cooling melt, continued movement compressed and deformed the surface into the wrinkled texture. Along the ridge crests, the crust has been broken up into slabs.

The margin of one impact melt pools reveals a fascinating story (right hand side of image [C]). A series of northeast-trending disturbed zones, 25-50 m wide, cut the flow. The zones are likely are shear planes along which differential movement of the flow has occurred. These planes form boundaries between portions of the flow that moved laterally (to the lower left) by different amounts; the shearing movement has broken up the surface crust of the flow into a numerous small blocks. The edge of the flow is marked by a rubble zone.

(C) Shearing along the western margin of the pool. View the 1000 x 1000px detail image, HERE [NASA/GSFC/Arizona State University].

The southern end (D) is defined by a series of small lobes which probably represent breakout of still molten impact melt from the edge of the pool. The edges of the lobes are marked by plates of broken crust which presumably were rafted away from the original edge. The large lobe would have broken out from the end of the pool and flowed and broadened into a lobe about 200 m long and 300 m wide.

Simulated oblique view of
the southeastern flank of Tycho, from "Tycho's flash-frozen inferno," a
discussion of the stream of impact melt and its cascade down the rim of
the 109 million year old relatively recent impact, posted here last
November. Jeff Plescia of Arizona State University's Lunar
Reconnaissance Orbiter Camera (LROC) science team covers the topic in
more recent images and greater detail below [NASA/GSFC/USGS/Arizona
State University/Google Earth]

On May 28 LRO was slewed 59° to the west, from an altitude of 92 km (57 miles) and captured a dramatic view of the Apollo 16 landing site.

During the Apollo 16 mission Ken Mattingly passed over the site several times at an altitude of 120 km (75 miles). If you imagine yourself in the Command Module, then this view is close to what you would have seen.

The lighting is nearly identical to that of when the Lunar Module Orion set down on the Moon.

On the second day of surface activities John Young and Charlie Duke headed south to sample material from Stone mountain and ejecta from South Ray crater. They headed south and turned east climbing up the flank of Stone Mountain. Imagine the view that Young and Duke had from Cinco crater (Station 4)! From their vantage point some 300 meters above the LM, the astronauts could see all the way from South Ray crater to North Ray crater.

Full resolution field of view from a LROC Wide Angle Camera (WAC) monochrome (604nm) montage, swept up from a mere 38.27 kilometers, in orbit 11299, December 3, 2011; 52.3 meters resolution. Like the Featured Image, the illumination from the east, at a 69.57° angle of incidence, is similar to the lighting during the Apollo 16 expedition in April 1972 [NASA/GSFC/Arizona State University].

With the annotated version you can easily retrace the routes followed by Young and Duke as they spent three days exploring this highland landing site. Read a detailed reconstruction of the astronaut activities through the Apollo Lunar Surface Journal.

What did they find at House Rock? Why was Shadow Rock an important science target? Is Baby Ray crater older or younger than South Ray crater? Then imagine yourself picking up where the Apollo astronauts left off over forty years ago!

When will we return to the Moon?

Dive into the full resolution oblique shot of the Apollo 16 site, HERE.

Retrace the astronaut traverses in an annotated version of oblique image, HERE.